There is a way. Years of school and practice coding. Forget about porting current MAME though, you'll need to start with an older version that's already been ported to Android (MAME4DROID, and I'm only guessing, because ARM), then you'll likely need to code your own gui on top of it.
EDIT: MAME4DROID was also ported to compile for iOS, but I'm pretty sure that's not a good starting point. It could give you ideas of how things are ported, I guess...